node.js - path.join vs path.resolve with __dirname

Question

Is there a difference when using both path.join and path.resolve with __dirname for resolving absolute path in Node.js?

Should one of them be preferred when being used like that (absolute path resolutions are 90% of use cases)?

I.e.

const absolutePath = path.join(__dirname, some, dir);

vs.

const absolutePath = path.resolve(__dirname, some, dir);

Both methods normalize path.

Answer 1

Yes there is a difference between the functions but the way you are using them in this case will result in the same outcome.

path.join returns a normalized path by merging two paths together. It can return an absolute path, but it doesn't necessarily always do so.

For instance:

path.join('app/libs/oauth', '/../ssl')

resolves to app/libs/ssl

path.resolve, on the other hand, will resolve to an absolute path.

For instance, when you run:

path.resolve('bar', '/foo');

The path returned will be /foo since that is the first absolute path that can be constructed.

However, if you run:

path.resolve('/bar/bae', '/foo', 'test');

The path returned will be /foo/test again because that is the first absolute path that can be formed from right to left.

If you don't provide a path that specifies the root directory then the paths given to the resolve function are appended to the current working directory. So if your working directory was /home/mark/project/:

path.resolve('test', 'directory', '../back');

resolves to

/home/mark/project/test/back

Using __dirname is the absolute path to the directory containing the source file. When you use path.resolve or path.join they will return the same result if you give the same path following __dirname. In such cases it's really just a matter of preference.